Camera module

ABSTRACT

A camera module includes a lens holder, a lens module, an image sensor chip, and a printed circuit board. The lens module is received in the lens holder. The lens module includes a lens barrel and at least one lens received in the lens barrel. The image sensor chip has a photosensitive area configured for receiving light transmitted through the lens module. The printed circuit board defines a top surface for receiving both the image sensor chip and the lens barrel thereon and an opposite bottom surface thereon. The bottom surface defines a plurality of recesses thereon for receiving the corresponding electronic elements therein by adhesives.

TECHNICAL FIELD

The present invention relates to the art of camera modules and,particularly, to a camera module with small-sized image sensor chippackage used in portable electronic devices.

BACKGROUND

Because of advances in micro-circuitry and multimedia technology,digital cameras are now in widespread used. High-end portable electronicdevices, such as mobile phones and Personal Digital Assistants (PDAs),are being developed to be increasingly multi-functional. Many of theseportable electronic devices are popularly equipped with digital cameras.To facilitate portability, such portable electronic devices tend to becompact, slim, and light. Accordingly, digital cameras incorporated inthe portable electronic devices have also been required to be reduced insize and weight, yet to remain cost-effective.

Referring to FIG. 5, a typical digital camera module 1 includes a lensmodule 2, a lens holder 3, and an image sensor chip 4. The lens module 2includes a barrel 21 and a lens 22 received in the barrel 21. The barrel21 is partially received in and is threadingly engaged with the lensholder 3. An IR (infra-red) cut filter 6 is adhered to a top surface 40of the image sensor chip 4 to protect the image sensor chip 4 againstdamage from IR light. The image sensor chip 4 is typically mounted on aprinted circuit board 5. The image sensor chip 4 has a photosensitivearea 41 formed on the top surface 40 thereof. The photosensitive area 41is configured for receiving light signals transmitted through the lensmodule 2. A plurality of chip pads is formed on the top surface 40 forsurrounding the photosensitive area 41. A plurality of board pads isformed on the printed circuit board 5 to electrically connect to thecorresponding chip pads via wires. A plurality of elements 7 is formedon the periphery of the printed circuit board 5 around the board pads.The lens holder 3 is mounted on the printed circuit board 5 so that theimage sensor chip 4, the chip pads, the board pads, and the wires arereceived therein.

In the camera module 1, the printed circuit board 5 needs to providesufficient space not only for the image sensor chip 4, the driver 7, andthe wires but the lens holder 3 as well. To minimize the size and volumeof the camera module 1 to a certain degree, an end portion 32 of thelens holder 3 is made thin. However, such a thin lens holder 3 is noteasily manufactured by an injection molding method. This difficultyresults in a relatively high cost. As such, the camera module 1 has notproven to be economically suitable for slim and compact electronicproducts.

What is needed, therefore, is a camera module that is both compact andeconomical to produce.

SUMMARY

In accordance with a present embodiment, a camera module includes a lensholder, a lens module, an image sensor chip, and a printed circuitboard. The lens module is received in the lens holder. The lens moduleincludes a lens barrel and at least one lens received in the lensbarrel. The image sensor chip has a photosensitive area configured forreceiving light transmitted through the lens module. The printed circuitboard defines a top surface for adhering the image sensor chip and thelens barrel thereon and an opposite bottom surface thereon. The bottomsurface defines a plurality of recesses for receiving the correspondingelectronic elements therein fixed by adhesives.

Other advantages and novel features will be drawn from the followingdetailed description of at least one preferred embodiment, whenconsidered in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present camera module can be better understood withreference to the following drawings. The components in the drawings arenot necessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the camera module. Moreover, inthe drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic, cross-sectional view of a camera module inaccordance with a first present embodiment;

FIG. 2 is a schematic, cross-sectional view of a camera module inaccordance with a second present embodiment;

FIG. 3 is a schematic, cross-sectional view of a camera module inaccordance with a third present embodiment;

FIG. 4 is a schematic, cross-sectional view of a camera module inaccordance with a fourth present embodiment; and

FIG. 5 is a schematic, cross-sectional view of a typical related cameramodule.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present camera module will now be described in detailbelow with reference to the drawings.

Referring to FIG. 1, a camera module 100, in accordance with a firstpreferred embodiment, includes a lens module 10, a lens holder 20, animage sensor chip 30, and a printed circuit board (PCB) 40. The lensmodule 10 is partially received in the lens holder 20. The image sensorchip 30 is fixed to the lens holder 20.

The lens module 10 includes a lens barrel 11 and at least one lens 12.The lens barrel 11 is configured for receiving the at least one lens 12therein, and has an external thread 111 formed thereon. In otherembodiments, the at least one lens 12 could include two or more lensesreceived in the lens barrel 11.

The lens holder 20 has a front end 25 and a rear end 26, opposite to thefront end 25, and defines a receiving cavity 21 penetrating/extendingthrough the lens holder 20 from the front end 25 to the rear end 26. Aninternal thread 22 is formed on part of an inner surface of the lensholder 20, beginning at or adjacent to the front end 25. The lens barrel11 is partially received in the lens holder 20 by engaging the externalthread 111 of the lens barrel 11 with the internal thread 22 of the lensholder 20.

The image sensor chip 30 is usefully disposed directly on the PCB 40.The image sensor chip 30 has a first surface facing towards the lensmodule 10 and a second surface opposite to the first surface. The imagesensor chip 30 has a photosensitive area 31 configured (i.e., structuredand arranged) for receiving light transmitted through the lens module10. A plurality of chip pads 32 is formed on the first surfacesurrounding the photosensitive area 31. An adhesive 33 is applied inpatches between the photosensitive area 31 and the chip pad 32 orapplied as a continuous layer surrounding the photosensitive area 31 andcovering the chip pad 32. In this embodiment, the adhesive 33 is appliedsurrounding the photosensitive area 31 and covering the chip pad 32. Theadhesive 33 is, beneficially, made of a curable adhesive material, forexample, a silicone, epoxy, acrylic, or polyamide adhesive.

A transparent layer 50 is adhered to the first surface of the imagesensor chip 30 via the adhesive 33. The transparent layer 50 and theadhesive 33 cooperatively form a package structure for thephotosensitive area 31.

The PCB 40 includes a top surface 41 and a bottom surface 42 opposite tothe top surface 41. The image sensor chip 30 is adhered to the middleportion of the top surface 41. A plurality of board pads 45 is formeddirectly on the top surface 41 surrounding the image sensor chip 30.Each board pad 45 is electrically connected to the corresponding chippad 32 via a respective wire. The wires are advantageously made of ahighly conductive, oxidation-resistant (i.e., a quality promoting goodlong-term conductivity) material, such as gold, aluminum, or an alloythereof. A first recess 43 is formed in the middle of the bottom surface42 and is provided for adhering at least one electronic element 44 on abottom portion of the first recess 43. The electronic elements 44 can,advantageously, be passive or compositive elements. The electronicelement 44 is electrically connected to the PCB 40. In order to preventdust or vapor entering the first recess 43 and affecting the performanceof the electronic elements 44, glue can be used to cover the firstrecess 43 to protect the electronic elements 44.

Referring to FIG. 2, a camera module 200, in accordance with a secondpreferred embodiment, is similar to the camera module 100 of the firstembodiment. In this embodiment, the bottom surface 142 of the PCB 140defines a step-shaped recess in the middle thereof. The step-shapedrecess comprises a first recess 143 formed on an upper portion thereofand a second recess 146 coaxially formed on a lower portion thereof. Thediameter of the second recess 146 is greater than that of the firstrecess 143 to form a middle surface 147 between the first recess 143 andthe second recess 146. At least one zero voltage point 148 is formed onthe middle surface 147 thereof for adjusting the voltage of theconductors connected to the zero voltage point 148 to zero. A coverplate 160 made from electrical material and received in the secondrecess 146 defines at least one electronic layer received therein and anexternal point 161 formed on a surface nearest the first recess 143. Inthis embodiment, the zero voltage point 148 is four voltage points andthey are respectively positioned on the corresponding corners of themiddle surface 147. The number of external points 161 is equal to thatof the zero voltage points 148. The electronic layer of the cover plate160 is electrically connected to the zero voltage points 148 by theexternal points 161, thereby the cover plate 160 can preventelectromagnetic waves generated by the electronic elements 144 receivedin the first recess 143 from affecting the image sensor chip 130. Otherconfigurations of the second embodiment are the same as that of thefirst embodiment, and so are not described in detail.

Alternatively, the zero voltage points 148 may be omitted, and theexternal points 161 formed on the bottom surface 142 of the PCB 140,thereby the cover plate 160 is directly adhered to the middle surface147. During assembly of the camera module 200 to a main printed board(not shown), the external points 161 of the cover plate 160 areelectrically connected to the main printed board to preventelectromagnetic waves generated by the electrical elements 144 receivedin the first recess 143 from affecting the image sensor chip 130 of thecamera module 200.

Referring to FIG. 3, a camera module 300, in accordance with a thirdpreferred embodiment, is similar to the camera module 200 of the secondembodiment. In this embodiment, the electrical element 244 is directlyadhered to the cover plate 260, not in the bottom of the first recess243. Other configurations of the third embodiment are the same as thatof the second embodiment, and so are not described in detail.

Referring to FIG. 4, a camera module 400, in accordance with a fourthpreferred embodiment, is similar to the camera module 100 of the firstembodiment. In this embodiment, the second recess 346 is formed in themiddle of the top surface 341, not in the bottom surface 342 of the PCB340. The image sensor chip 330 is received in the second recess 346, andthe board pad 345 is formed on an exposed portion of the top surface 341surrounding the second recess 346. Other configurations of the fourthembodiment are the same as that of the first embodiment, and so are notdescribed in detail.

In the camera modules, the electronic elements are adhered in the firstrecess formed on the bottom surface, not positioned on the top surfaceof the PCB. Therefore, special space is not need adjacent the PCB forpositioning of the electronic elements thereon. Thus, the problematicthin walls of the related art can be replaced by more convenientlyformed and stronger walls, or the space freed up could be used so thatless precision in placement of elements is required, due to greaterspace availability for such, which could reduce manufacturing costs, orthe camera modules could be made having a smaller diameter allowing forsmaller electronic devices utilizing same.

Although the present invention has been described with reference toparticular embodiments, it is not to be construed as being limitedthereto. Various alterations and modifications can be made to theembodiments without in any way departing from the scope or spirit of thepresent invention as defined in the appended claims.

1. A camera module comprising: a lens holder defining a receivingportion thereof; a lens module partially received in the receivingportion of the lens holder, the lens module comprising a lens barrelmovably engaged in the lens holder and at least one lens received in thelens barrel; an image sensor chip package mounted to the lens holder,comprising: a circuit board defining a top portion formed thereof, abottom portion opposite to the top portion, and a plurality of boardpads arranged on the top portion; an image sensor chip mounted on thetop portion of the circuit board, the image sensor chip comprising aphotosensitive area configured for receiving light transmitted throughthe lens module, and a plurality of chip pads formed surrounding thephotosensitive area; a plurality of wires each electrically connectingone of the plurality of chip pads of the image sensor chip with acorresponding one of the plurality of board pads of the circuit board;an adhesive means applied surrounding the photosensitive area andcovering the plurality of chip pads; a transparent layer mounted to theimage sensor chip via the adhesive means, the transparent layer togetherwith the adhesive means sealing the photosensitive area of the imagesensor chip; wherein the lens holder is adhered to the top portion ofthe circuit board, the bottom portion of the circuit board defines atleast one recess for receiving at least one electronic element therein,the at least one electronic element electrically connected to thecircuit board; each of the at least one recess has a step-shapedconfiguration and comprises a first recess formed on an upper portionthereof and a second recess coaxially formed on a lower portion thereof;a cover plate received in the second recess for covering the firstrecess; a plurality of zero voltage points formed on the periphery of amiddle surface between the first recess and the second recess thereoffor adjusting the voltage of conductors connected to the plurality ofzero voltage points to zero; and a plurality of external points alsoformed on the periphery of the cover plate to electrically connect tothe corresponding zero voltage points.
 2. The camera module as claimedin claim 1, wherein the diameter of the second recess is greater thanthat of the first recess to form the middle surface between the firstrecess and the second recess.
 3. The camera module as claimed in claim1, wherein the at least one electronic element is adhered to an upperportion of the cover plate, and the plurality of external points formedsurrounding the electronic elements.
 4. The camera module as claimed inclaim 1, wherein the at least one electronic element is a passiveelements or compositive elements.
 5. The camera module as claimed inclaim 1, wherein another recess is formed at the top portion of thecircuit board, the image sensor chip received in the another recess. 6.The camera module as claimed in claim 1, wherein the lens holder has aninternal thread formed on an inner surface, the lens barrel has anexternal thread corresponding to and screwing with the internal threadof the lens holder, the external thread is formed on an external surfaceof the lens barrel.
 7. A camera module comprising: a lens holderdefining a receiving portion thereof; a lens module partially receivedin the receiving portion of the lens holder, the lens module comprisinga lens barrel movably engaged in the lens holder and at least one lensreceived in the lens barrel; an image sensor chip package mounted to thelens holder, comprising: a circuit board defining a top portion formedthereof, a bottom portion opposite to the top portion, and a pluralityof board pads arranged on the top portion; an image sensor chip mountedon the top portion of the circuit board, the image sensor chipcomprising a photosensitive area configured for receiving lighttransmitted through the lens module, and a plurality of chip pads formedsurrounding the photosensitive area; a plurality of wires eachelectrically connecting one of the plurality of chip pads of the imagesensor chip with a corresponding one of the board pads of the circuitboard; an adhesive means applied surrounding the photosensitive area andcovering the plurality of chip pads; a transparent layer mounted to theimage sensor chip via the adhesive means, the transparent layer togetherwith the adhesive means sealing the photosensitive area of the imagesensor chip; wherein the lens holder is adhered to the top portion ofthe circuit board, the bottom portion of the circuit board defines atleast one recess for receiving at least one electronic element therein,the at least one electronic element electrically connected to thecircuit board; each of the at least one recess has a step-shapedconfiguration and comprises a first recess formed on an upper portionthereof and a second recess coaxially formed on a lower portion thereof;the diameter of the second recess is greater than that of the firstrecess to form a middle surface between the first recess and the secondrecess; a cover plate made from electrical conductive material andreceived in the second recess for covering the first recess; and aplurality of zero voltage points is formed on the periphery of themiddle surface thereof for adjusting the voltage of conductors connectedto the plurality of zero voltage points to zero, and a plurality ofexternal points is also formed on the periphery of the cover plate toelectrically connect to the corresponding zero voltage points.